The present invention generally relates to the pollination of crops by bees, and more specifically to a unit for the storage and emergence of solitary bees and a method of utilizing the same.
Many crops benefit from pollination by bees, and some are highly dependent on bee pollination. These include the following food crops—almond, apple, avocado, blueberry, canola, cantaloupe, cherry, blueberry, cranberry, cucumber, kiwifruit, nectarine, peach, pear, pepper, plum, prune, raspberry, squash (including pumpkin and gourd), strawberry, sunflower, and tomato; and also crops for seed production, such as alfalfa, asparagus, beet, cabbage and other crucifers, carrot, clover and onion. Crops grown indoors such as in tunnels and glasshouses, and crops grown in very large areas frequently suffer from lack of natural pollinators.
Most commercial pollination is carried out using honeybees. The present invention is directed at an apparatus and method for improving the utilization of solitary bees as managed pollinators.
Solitary bees have a wide range of nesting habits. Some create cavities in which to nest, by mining or constructing cells; others (among them many species of Megachilid bee, such as Osmia and Megachile species) search for existing cavities, such as hollow plant stems, beetle borings in timber, pre-used nests created by other insects, and naturally occurring crevices. A female bee collects pollen which she packs into the cavity, then lays an egg on the pollen. The cavity is sealed containing one or several eggs which hatch into larvae and eat the stored pollen. Development is completed within the cavity. Eventually, adult bees emerge from the cavity to mate and continue the cycle.
Several species of solitary bee can be encouraged to use artificial nests. Such artificial nests can be used as trap nests to study existing populations; to improve habitats in order to attract bees or to boost populations; and to manage bees as pollinators in order to produce food crops and seed crops, and enhance pollination of wild flowers.
A number of strategies for artificial nests for solitary bees have been produced that seek to mimic the above-mentioned natural cavities. Nests may be formed from tubes. Hollow plant stems in which bees would naturally nest, such as reeds or bamboo, can be bundled together. These unsophisticated forms of nests are widely known and described, for example in Bosch J and Kemp W, 2001, “How To Manage the Blue Orchard Bee As An Orchard Pollinator”, Sustainable Agriculture Network, p 20. Instead of using natural cavities provided by hollow plant stems, artificial tubes have also been widely used. These tubes include craft straws or drinking straws, as described in McGregor S E 1976, “Insect Pollination of Cultivated Crop Plants”, United States Department of Agriculture, p 37. Thin-walled tubes and stems are vulnerable to parasitoid attack, so the use of thick-walled cardboard tubes has increased. Various cardboard tubes have been used, some incorporating a paper liner to improve removal and examination of the developing bees and also to deter parasitoid attack.
Nests may also be formed from grooved boards. Nests consisting of stacks of grooved boards are well known. The grooved boards are formed in such a manner that when stacked, they create an array of cavities therein. The grooves may be formed in a U-shape, which coincides with a flat face of an adjacent board to form a cavity, as described in Bosch J and Kemp W, 2001, “How To Manage the Blue Orchard Bee As An Orchard Pollinator”, Sustainable Agriculture Network.
Alternatively, semi-circular grooves may be formed on both sides of each board of the stack, the semi-circular grooves of adjacent boards being aligned to create an array of cavities having a circular cross-section, as described in U.S. Pat. No. 5,372,535 and U.S. Pat. No. 5,618,220.
The flowering of most of the crop plants referred to above takes place over a limited period. In order to achieve effective pollination on a commercial scale it is necessary to ensure that bees are on site and available to forage on the flowers during that period. When honeybees are used, this is a matter of bringing hives with large populations of workers to the site in time. Solitary bees have a different life cycle which requires an entirely different management strategy.
In the spring and early summer, solitary bees in the wild are stimulated to start the process of emergence by longer periods of higher temperature. It may be that a small grower of say apples will be fortunate in that a wild population of solitary bees emerges reliably around the time that the trees flower. However commercial pollinators must be in a position to influence the time of emergence to delay or bring forward the activity of the bees to match the flowering of the target crop.
In the wild, solitary bees overwinter either as dormant adults or as prepupae. The emergence of certain species of solitary bee, for example Osmia rufa, O. cornuta and O lignaria, may take place over an extended period, in cases up to a month. In addition the males start to emerge first, with the females following a few days or a week later. Although the general pattern of emergence is well known, it can be difficult to predict with accuracy what percentages of males and females will have emerged by a certain date under a certain temperature regime. The use of degree-day models is well known in agriculture and science to predict various biological phenomena such as the commencement of growth of specific plants, the opening of flowers or buds, or the activity of insects, but the application of degree-day modeling to management of solitary bees is not precise enough at the present time.
One known approach to providing flying solitary bees on crops to be pollinated is to warm the cocoons until sufficient active adults have emerged. These bees are chilled again, then transported to the pollination site and released. This procedure means that the earliest of the emerging females are held for a number of days after emergence, before deployment in the field, a factor which may contribute to the high dispersal rate that is sometimes observed when active adult bees are released direct into the orchard. This may require many more bees to be released than are actually necessary to carry out the pollination. Another approach is to warm the cocoons (either by staged temperature increases or directly from chilled temperature to incubation temperature) to a point at which it is calculated the bees are close to emergence, then transport the cocoons to the pollination site and allow the bees to emerge under ambient conditions. A drawback of this procedure is that if temperatures drop the emergence may be delayed for a considerable period, so that the number of flying bees is reduced or even zero at the critical period for pollination.
After the flowers have fallen from the crop, and no females are still active, the nests are removed from the orchard, field, glasshouse, etc and transported to a central facility for further handling. In the known practice, this may include emptying of nests; washing or cleaning the cocoons; sorting the cocoons by sex; examining for parasites and disease; carrying out hygienic measures; storing the cocoons in appropriate conditions; examining bees to determine stage of development; placing in cold store for winter; removing from the cold store; and deploying emerging adults into orchards, fields, etc.